Arduino: build a line-following robot
A 2WD robot that follows a black electrical-tape line using three IR reflectance sensors. Bang-bang control done honestly, PID optional.
Platform
Arduino
The classic. Cheap, simple, and still the right call when you just need a chip to read a sensor.
40 tutorials
Arduino: a full traffic light with pedestrian button
Build a traffic light with a pedestrian crossing button using a proper state machine. The project that teaches event timing without delay().
Arduino: Simon-says memory game
Build the Simon memory game with 4 buttons, 4 LEDs, and a buzzer. State machines, tone(), and the game loop that scales to any difficulty.
Arduino: motion-activated night security light
A real outdoor-style light: PIR triggers, an LDR confirms it is dark, a relay drives a 12V lamp. The AND logic that stops false triggers.
Arduino: build a light-following robot with LDRs
A 2WD robot that chases a flashlight beam using two LDR eyes and bang-bang steering. Phototaxis for twelve dollars of parts.
Arduino: read a 4x4 membrane keypad with 8 pins
Read a 4x4 keypad with 8 Arduino pins instead of 16 by scanning rows and columns. The matrix-scan trick behind every keyboard ever made.
Arduino: animations on an 8x8 LED matrix (MAX7219)
Drive an 8x8 LED matrix with a MAX7219 and Arduino. Build frame-based animations: a smiley, a wave, and a scrolling pixel text. One chip, three wires.
Arduino: real timekeeping and alarms with the DS3231 RTC
Give your Arduino a real clock with the DS3231 RTC module. Set the time, read it back, and fire alarms that survive power loss, drift, and reboot.
Arduino: control it from an Android app with MIT App Inventor
Drive an Arduino over Bluetooth from an Android app you build yourself with MIT App Inventor, no Java, one HC-06 module, two-way control.
Arduino: build a digital clock with DS3231 + OLED
Build a desk clock that never drifts: a DS3231 RTC keeps time, a 0.96 inch SSD1306 OLED shows it big. Two I2C devices on the same two wires, plus a button to set it.
Arduino: long-range 2.4 GHz radio links with nRF24L01
Two Arduinos talking over 2.4 GHz with nRF24L01 modules, no WiFi, no phone, one capacitor and a library. Sensor links that run for months.
Arduino: electronic dice roller with 7-segment display
Roll a die with a button press: a 7-segment display shows 1 to 6 with a tumble animation. Direct-drive wiring, a segment map, and honest randomness on the Uno.
Arduino: Ethernet web server when Wi-Fi is not an option
Put an Arduino on your LAN with a W5500 Ethernet module and serve sensor pages from any browser. The wired path when Wi-Fi drops, roams, or is not allowed.
Arduino: location and time from a NEO-6M GPS module
Read latitude, longitude, and the exact UTC time from a $12 NEO-6M GPS module over serial. Wiring, the TinyGPS++ library, and why the fix takes 5 minutes outside.
Arduino: build a digital scale with a load cell and HX711
Turn a $8 load cell into a working digital scale with the HX711 amp and an Arduino Uno. Wiring, the calibration step everyone skips, and 1 g resolution.
Arduino: decode any IR remote with the IRremote library
Wire a 3-pin IR receiver to an Arduino and decode any TV or AC remote with the IRremote library. NEC, Sony, RC5, and the switch statement that turns buttons into actions.
Arduino: build an obstacle-avoiding robot from scratch
A 2WD Arduino robot that drives forward and dodges what is in front of it, using an HC-SR04 on a servo and an L298N driver. The full build, wiring to behavior.
Arduino: read high temperatures with a K-type thermocouple and MAX6675
Wire a K-type thermocouple and a MAX6675 to an Arduino and read oven, kiln, and solder-pot temperatures up to 1024 C. Includes the polarity trap.
Arduino: read water quality with the TDS module
Measure total dissolved solids with the Gravity TDS module on an Arduino: clean wiring, temperature compensation, calibration, and what TDS cannot tell you.
Arduino: voice control with a DFPlayer or voice-recognition module
Voice control on Arduino without the cloud: the DF2301Q offline voice module drives lights and sounds, and a DFPlayer Mini gives the project a voice back.
Arduino: build a gas alarm with the MQ-2
Build an MQ-2 gas and smoke alarm on an Arduino: wiring, warm-up, calibration, buzzer code, and the honest limits of a DIY detector.
Arduino: line-follower with the TCRT5000 array and PID
The PID line-follower: three TCRT5000 analog sensors feed one weighted error signal, and the robot steers in proportion to how far off the line it is.
Arduino: microwave radar motion detection with the RCWL-0516
Detect motion through walls and plastic with the RCWL-0516 microwave radar module. Doppler sensing that ignores temperature, sunlight, and thin drywall.
Arduino: datalogger with RTC + SD card for timestamped sensor files
Log sensor readings to an SD card with real timestamps from a DS3231 RTC. CSV files your spreadsheet opens directly, and a clock that survives power cuts.
Arduino: receive 433 MHz RF remote signals and replay them
Sniff, decode, and replay 433 MHz RF remotes (wireless doorbells, plug sockets) with a superheterodyne receiver and RCSwitch. One Arduino, two boards.
Arduino: drive a 4-digit display with the TM1637
Wire a TM1637 4-digit 7-segment display to an Arduino and print numbers, a clock, and a scrolling counter. Two pins, one library, no soldering.
Arduino: persist data with EEPROM, the right way
Save a calibration value or a small setting to EEPROM so it survives a power cycle. The 1 KB on the Uno is enough for hundreds of values if you use it carefully.
Arduino: read a rotary encoder, position and direction
Wire a rotary encoder to two interrupt pins and track position, direction, and speed. The pattern that lets a motor know where it is.
Arduino: drive a DC motor with the L298N H-bridge
Wire an L298N module to an Arduino and control a DC motor forward, reverse, and at variable speed with PWM. The H-bridge pattern that runs most hobby robots.
Arduino: hardware interrupts, the right way to react to events
Wire a button to an interrupt pin and react to it instantly. The pattern that makes pin-change detection feel like magic, and the rules you cannot break.
Arduino: read an HC-SR04 ultrasonic distance sensor
Wire an HC-SR04 to an Arduino and read distance in centimeters. The 40 kHz chirp, the trigger pulse, the echo timing, and the math that turns a microsecond count into a number you can use.
Arduino: the watchdog timer, recover from hangs automatically
Add a watchdog timer to your Arduino sketch so the chip resets itself when it hangs. The pattern that keeps field-deployed projects from being bricked by a stuck sensor.
Arduino: drive a 28BYJ-48 stepper motor with a ULN2003 driver
Wire a small stepper motor to an Arduino using the ULN2003 driver board. Precise position control without the expensive hardware.
Arduino: control relays for home automation
Drive a relay module from an Arduino to switch mains-powered devices. The most common home automation building block, with all the safety stuff included.
Arduino: drive a 16x2 LCD display (with I2C backpack)
Add a 16x2 character LCD to your Arduino using the I2C backpack. Show text, custom characters, and read sensor values on a screen.
Arduino: read temperature with a DS18B20 one-wire sensor
Wire a DS18B20 temperature sensor to an Arduino using the OneWire protocol. Multiple sensors on one pin, accurate to 0.5C.
Arduino: use I2C to talk to sensors and displays
I2C is the two-wire protocol that connects most Arduino sensors. This tutorial covers the wiring, the address scan, and the most common gotchas.
Arduino: control a servo motor
Drive a hobby servo (SG90, MG996R) from an Arduino. The shortest path from Arduino to 'something moved.'
Arduino: read a potentiometer and print the value
Wire a 10k potentiometer to an Arduino analog pin and read its position with analogRead. The second project after blink.
Arduino: blink an LED (the classic first project)
The minimum Arduino sketch. Blink the onboard LED on pin 13. If you have never programmed an Arduino, start here.